These ships would have rivaled the Imperial Japanese Yamato class and America's planned Montana class in size if any had been completed, although with significantly weaker firepower: nine 406-millimeter (16 in) guns compared to the nine 460-millimeter (18.1 in) guns of the Japanese ships and a dozen 16-inch (406 mm) on the Montanas.

Construction of the other three ships was suspended shortly after Nazi Germany invaded the Soviet Union in June 1941, and never resumed.

Ansaldo & C. proposed a ship of 42,000 long tons (43,000 t) standard displacement with nine 16-inch (406 mm) guns, in size and appearance similar to the Italian battleship Littorio then under construction by the company.

The first Tactical-Technical Requirement (abbreviated in Russian as ТТZ) for the large battleship design was issued on 21 February 1936 but proved too ambitious, specifying nine 460 mm guns and a speed of 36 knots (67 km/h; 41 mph) on a displacement of 55,000 tons.

[Note 1] The TTZ was revised in May 1936 by Admiral Vladimir Orlov, Commander of the Soviet Navy, reducing speed to 30 knots (56 km/h; 35 mph), and weakening the secondary and anti-aircraft batteries.

Shortly afterward, the Soviet Union signed the Anglo-Soviet Quantitative Naval Agreement of 1937 and agreed to follow the terms of the Second London Naval Treaty that limited battleships to a displacement of 35,560 metric tons (35,000 long tons), although they did add a proviso that allowed them to build ships of unlimited size to face the Imperial Japanese Navy if they notified the British.

The issue was resolved by General Secretary Stalin at a meeting on 4 July when he agreed to increase displacement to about 56,000 tons.

[6] The timing of the redesign proved to be inauspicious as the Great Purge was spreading through the ranks of the military and related industries.

The original deadline for completion of design work by 15 October was missed, and an incomplete version was presented to the navy's Shipbuilding Administration the next month.

In the meantime, extensive and expensive testing was conducted on the ship's hull form, deck armor and torpedo protection; 27 million rubles were spent on experimental work in 1938 alone.

The underwater protection system was tested on fifteen one-fifth scale models and two full-sized experimental barges.

These tests proved that the torpedo belt system of multiple bulkheads was superior to the Pugliese system of a large tube filled with smaller sealed tubes, but it was too late to incorporate these test results into the design as construction was well underway by the time they were completed in late 1939.

[9] The hull form was very full-bodied, especially at the forward magazines, where the torpedo protection system added width to the beam.

Coupled with the relatively low length-to-beam ratio of 7.14:1, this meant that very powerful turbines were necessary to achieve even modest speeds.

[10] The Sovetsky Soyuz-class ships were provided with facilities to handle two to four KOR-2 flying boats which would be launched by the two catapults mounted on the stern.

[12] The steam turbines, and a license to build them, were originally going to be ordered from Cammell Laird in the United Kingdom, but their £700,000 cost was more than the Soviets wanted to pay.

Four single-reduction, impulse-reduction geared turbines were ordered from the Swiss firm, three to equip Sovetskaya Rossiya and one to serve as a pattern for the factory in Kharkov that was to build the remainder.

The normal fuel oil capacity was 5,280 metric tons (5,197 long tons), giving an estimated endurance of 6,300 nautical miles (11,700 km; 7,200 mi) at 14.5 knots (26.9 km/h; 16.7 mph) and 1,890 nautical miles (3,500 km; 2,170 mi) at full speed.

The guns fired 1,108-kilogram (2,443 lb) projectiles at a muzzle velocity of 830 m/s (2,700 ft/s); this provided a maximum range of 45,600 meters (49,900 yd).

Initially only eight mounts were planned when the ships began construction, but two more were added later, probably in January 1941, one on each side of the forward superstructure.

The plants tended to compensate by making the thicker plates harder, but this often made them more brittle and large numbers did not pass the acceptance tests.

The ships were intended to be able to remain afloat with any five adjacent compartments flooded or with three torpedo hits and the destruction of the unarmored above-water side.

However, only four were actually laid down before the outbreak of World War II forced the Soviets to reassess their ambitious plans.

[25] The Soviet shipbuilding and related industries proved to be incapable of supporting the construction of so many large ships at the same time.

Shipbuilding steel proved to be in short supply in 1940, and a number of batches were rejected because they did not meet specifications.

A prototype boiler was supposed to have been built ashore for evaluation, but it was not completed until early 1941, which further complicated the production plan.

She was only lightly damaged by German air attacks and bombardments, and, as some material had been used during the siege of Leningrad, she was estimated to be 19.5% complete after the end of the war.

Stalin's expressed desire to see one of the Project 23-class ships completed only delayed the decision to scrap her; this was ordered on 29 May 1948 and was well underway by April 1949.

They were forced to evacuate Mykolaiv on 17 March 1944 and demolished the supporting blocks under her port side before they left, which gave her a list between 5 and 10 degrees and made her a total loss.

[32] Sovetskaya Gruziya (Советская Грузия-Soviet Georgia) was planned to be laid down in 1941 at the Baltic Works, but this was cancelled due to the invasion of the Soviet Union.